Funtional Similarities between the Cytoplasmic Organelles of Melanocytes and the Mitochondria of Hepatocytes

Prevention of Congenital Otolith Defect in Pallid Mutant Mice by Manganese Supplementation

“…Therefore, the inner ear of pa/+ mice should contain more manganese than that of palpa, a possibility to be examined in detail. A similar hypothesis, suggesting that melanin may chelate manganese, was advanced to explain the correlation between manganese concentration and pigmented tissues ( COTZIAS, PAPAVASILIOU and MILLER 1964; VAN WOERT, NICHOLSON and COTZIAS 1965). Our evidence indicates that albino animals, presumably containing amelanotic melanocytes in the inner ear, also possess the manganese reservoir.…”

Role of calcium ions in the control of embryogenesis of Xenopus. Changes in the subcellular distribution of calcium in early cleavage embryos after treatment with the ionophore A23187.

“…(b) Ion analysis of the subcellular fractions (Table V) confirms that [Ca 2+] rises in the cytosol, probably after release from the yolk platelets and/ or pigment granules, and that the mitochondria attempt to correct this by taking up Ca 2+. It has been suggested (32) that the bulk of the cell Ca 2+ is associated with the pigment granules and yolk platelets in the early cleavage embryos of Rana pipiens and that amphibian liver melanocytes have functional similarities with mitochondria (53). The pigment granules in the stage 5 eml~ryos are sited in the periphery of the cells, close to the layer of subcortical mierofilaments.…”

A Rational for Novel Anti-NeuroOncology Drugs

“…Thus, melanin is a polymer of indole-5, 6-quinone which is highly electrophilic due to its conjugated structure and capable of attracting, storing and/or transferring electrons as electrical energy [30,31,34]. DM-CHOC-PEN treatment induced ROS formation via the melanin system resulting in cancer cell death -an end point.…”

“…Melanin is far from being an end-product of oxidation [34][35][36][37]. At a glance the existence of energy bands are obvious from the highly conjugated heterocyclic indole quinone structure for melanin (Fig.…”

“…Clusters of melanin laden cells contained significantly elevated concentrations of DM-CHOC-PEN, as compared to the amelanotic variant; a possible storage site for the drug [31]. The initial DOPA → DOPA quinone transformation is catalyzed by tyrosinase (DOPA oxidase) intracellular [32][33][34][35]. However, the red-ox potential for DM-CHOC-PEN is sufficient to catalyze the conversion with excess melanin formation per the Rapier Scheme below [32].…”